Fair Value Measurement - Quantitative Information About Level 3 Fair Value Measurements for Financial Instruments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Fair Value Inputs Assets Quantitative Information [Line Items]
Loans held for sale, at fair value	$ 75,501	$ 62,593
Fair Value, Measurements, Recurring [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Loans held for sale, at fair value	75,501	62,593
Fair Value, Measurements, Recurring [Member] | Comparable Sales [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Loans held for sale, at fair value	$ 67,439	$ 53,761
Fair Value, Measurements, Recurring [Member] | Minimum [Member] | Comparable Sales [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Inputs, Time discount	0.00%	0.00%
Fair Value, Measurements, Recurring [Member] | Maximum [Member] | Comparable Sales [Member]
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Inputs, Time discount	1.80%	1.80%